Methods for identifying and using maintenance genes

ABSTRACT

This invention provides methods for discovering maintenance genes and for using maintenance genes. In one embodiment, the expression of at least three maintenance genes are measured and used as reference (or control) for comparing the expression of target genes in two or more biological samples.

RELATED APPLICATIONS

This application claims the priority of U.S. Provisional Application No. 60/161,000, filed on Oct. 21, 1999. The 60/161,000 application is incorporated herein by reference in its entirety.

This application is related to U.S. Pat. No. 6,033,860 which is incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

This application provides methods, compositions for identifying and using maintenance genes. The methods and compositions have extensive practical applications in areas such as drug discovery and diagnostics.

Housekeeping genes, or maintenance genes, are those genes constitutively expressed to maintain cellular function (See, Watson, J. D., N. H. Hopkins, J. W. Roberts, J. A. Steitz, A. M. Weiner, A. M. Molecular Biology of the Gene, Vol. 1, 1965). Previously tens of genes have been reported as putative housekeeping genes. The genes previously reported were identified by conventional methods and the putative housekeeping role of the gene product is an incidental observation (Duhig, T., C. Ruhrberg, O. Mor, M. Fried. The Human Surfeit Locus. Genomics, 52(1) 72-78, 1998; Hampsey, M. Molecular Genetics of the RNA Polymerase II General Transcriptional Machinery. Microbiol. Mol. Biol. Rev. 62(2):465-503, 1998; May, B. K., C. R. Bhasker, T. C. Cox.. Molecular Regulation of 5-Amniolevulinate Synthase Diseases Related to Heme Biosynthesis. Mol. Biol. Med., 7(5):405-421, 1990; Milner, C. M., R. D. Campbell. Genes, Genes and More Genes in the Human Major Histocompatibility Complex. Bioessays, 14(8):565-571, 1992; Rifkind, R. A., P. A. Marks, A. Bank, M. Terada, G. M. Maniatis, F. E. Reuben, E. Fibach. Erythroid Differentiation and the Cell Cycle: Some Implications from Murine Foetal and Erythroleukemic Cells. Ann. Immunol. 127:887-893, 1976; Roberston, H. A. Immediate-Early Genes, Neuronal Plasticity, and Memory. Biochem. Cell Biol., 70(9): 729-737, 1992; Russo-Marie, F. Macrophages and the Glucocorticoids. J Neuroimmunol, 40(2-3):281-286, 1992; Strehler, B. L., M. R. Freeman. Randomness, Redundancy and Repair: Roles and Relevance to Biological Aging. Mech. Aging Dev. 14(1-2) 15-38, 1980; and Yamamoto, T., Y. Matsui, S. Natori, M. Obinata. Cloning of a Housekeeping-Type Gene (MER5) Preferentially Expressed in Murine Erythroleukemia Cells. Gene 80 2:337-343, 1989).

Recently, massive parallel gene expression monitoring methods have been developed to monitor the expression of a large number of genes using nucleic acid array technology which was described in detail in, for example, U.S. Pat. Nos. 5,871,928, 5,800,992 and 6,040,138; de Saizieu, et al., 1998, Bacteria Transcript Imaging by Hybridization of total RNA to Oligonucleotide Arrays, NATURE BIOTECHNOLOGY, 16:45-48; Wodicka et al., 1997, Genome-wide Expression Monitoring in Saccharomyces cerevisiae, NATURE BIOTECHNOLOGY 15:1359-1367; Lockhart et al., 1996, Expression Monitoring by Hybridization to High Density Oligonucleotide Arrays. NATURE BIOTECHNOLOGY 14:1675-1680; Lander, 1999, Array of Hope, NATURE-GENETICS, 21(suppl.), at 3.

SUMMARY OF THE INVENTION

In one aspect of the current invention, methods for identifying a gene are provided. The methods include the steps of determining the expression of at least one hundred genes in at least two different types of tissues in two different developmental stages; and indicating a gene that is expressed at the same level in the tissues in the stages as the maintenance gene. In some embodiments, the method involves determining the expression of one thousand genes. In some preferred embodiments, the expression of candidate maintenance genes are measured in at least five different types of tissues. In one preferred embodiment, gene expression is determined using nucleic acid probe arrays such as high density oligonucleotide probe arrays, optical fiber arrays, spotted arrays (oligonucleotide, cDNA clones, cDNA fragments, etc.).

In preferred embodiments, a gene is considered as expressed at the same level if the variation of its expression is within 2, 5 or 10 fold. In another preferred embodiment, a gene is considered as expressed at the same level if the variation of its expression is not statistically significant.

In another aspect of the invention, methods are provided for comparing the expression of a gene in a plurality of biological samples. The methods include measuring the expression of at least three, five, seven or ten maintenance genes selected from the group of genes listed in table I or subset of the genes from table 1. The methods further include a step of evaluating the expression of the gene in the plurality of samples using the expression of the at least three, five or ten, maintenance genes. In some embodiments, the expression of a gene is adjusted using the expression of maintenance genes as a control. For example, the expression measurement of a target gene may be divided by the expression measurements of maintenance genes.

DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of the invention. While the invention will be described in conjunction with the preferred embodiments, it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the invention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention.

Methods for Gene Expression Monitoring:

Various techniques for large scale polymer synthesis and probe array manufacturing are known. Some examples include the U.S. Pat. Nos.: 5,143,854, 5,242,979, 5,252,743, 5,324,663, 5,384, 261, 5,405,783, 5,412,087, 5,424,186, 5,445,934, 5,451,683, 5,482,867, 5,489,678, 5,491,074, 5,510,270, 5,527,681, 5,550,215, 5,571,639, 5,593,839, 5,599,695, 5,624,711, 5,631,734, 5,677,195, 5,744,101, 5,744,305, 5,753,788, 5,770,456, 5,831,070, and 5,856,011, all of which are incorporated by reference in their entirety for all purposes.

The hybridization conditions between probe and target should be selected such that the specific recognition interaction, i.e., hybridization, of the two molecules, is both sufficiently specific and sufficiently stable. See, e.g., Hames and Higgins (1985) Nucleic Acid Hybridisation: A Practical Approach, IRL Press, Oxford. These conditions will be dependent both on the specific sequence and often on the guanine and cytosine (GC) content of the complementary hybrid strands. The conditions may often be selected to be universally equally stable independent of the specific sequences involved. This typically will make use of a reagent such as an alkylammonium buffer. See, Wood et al. (1985) “Base Composition-independent Hybridization in Tetramethylammonium Chloride: A Method for Oligonucleotide Screening of Highly Complex Gene Libraries,” Proc. Natl. Acad. Sci. USA, 82:1585-1588; and Krupov et al. (1989) “An Oligonucleotide Hybridization Approach to DNA Sequencing,” FEBS Letters, 256:118-122; each of which is hereby incorporated herein by reference. An alkylammonium buffer tends to minimize differences in hybridization rate and stability due to GC content. By virtue of the fact that sequences then hybridize with approximately equal affinity and stability, there is relatively little bias in strength or kinetics of binding for particular sequences. Temperature and salt conditions along with other buffer parameters should be selected such that the kinetics of renaturation should be essentially independent of the specific target subsequence or oligonucleotide probe involved. In order to ensure this, the hybridization reactions will usually be performed in a single incubation of all the substrate matrices together exposed to the identical same target probe solution under the same conditions. The hybridization conditions will usually be selected to be sufficiently specific such that the fidelity of base matching will be properly discriminated. Of course, control hybridizations should be included to determine the stringency and kinetics of hybridization. See for example, U.S. Pat. No. 5,871,928 which is hereby incorporated in its entirety for all purposes. Another factor that can be adjusted to increase the ability of targets to hybridize to probes, is the use of nucleic acid analogs or PNAs in the probes. They can be built into the probes to create a more uniform set of hybridization conditions across the entire array. See U.S. patent application Ser. No. 08/630,427 which is hereby incorporated by reference in its entirety for all purposes.

Samples are then washed and stained using a robotic liquid handling machine such as the GeneChip® Fluidic Station 400 (Affymetrix, Inc., Santa Clara, Calif.). Fluidics stations have been described in, for example, U.S. patent application Ser. Nos. 08/624,133 and 09/070,689. Finally, samples are placed on an automated loader which interfaces with a scanner such as the GeneArray™ scanner (Agilent Technologies). Scanners have been described in, for example, U.S. Pat. Nos. 5,578,832, 5,834,748,and 5,837,832, U.S. patent application Ser. Nos. 08/456,598, 09/238,131, 08/856,642 (now allowed), 09/295,214, 08/456,782, 08/999,188, U.S. Provisional Patent Application No. 60/106,397 and European Patent No. 97925605 each of which is hereby incorporated by reference in its entirety for all purposes.

The results are then analyzed using a computer program. Computer programs for the analysis of hybridization patterns on arrays have been described in, for example, U.S. Pat. Nos. 5,733,729, and 5,795,716, U.S. patent application Ser. Nos. 09/309,328, 09/020,743, 08/531,137, 09/158,765, 08/584,754, 09/049,805, 08/828,952, 08/948,896 and U.S. Provisional Patent Application Nos. 60/033,053 and 60/085,118 each of which is incorporated by reference in its entirety for all purposes.

Methods for Detecting Maintenance Genes:

The term housekeeping gene was broadly defined as a gene that is constitutively expressed. In this application, housekeeping genes are also referred to as maintenance genes. Generally, the housekeeping genes are critical to the processes that must be carried out for successful completion of the cell cycle and consequently play a key role in the activity and maintenance of every cell. It is likely that many genes may be constitutively expressed but in varying amounts in different tissues. These differences in level of abundance are probably more relevant to the characteristic function of each tissue than to the housekeeping/maintenance role.

Until recently the technical challenge of accurately measuring small differences in gene expression have been practically insurmountable, consequently there is little evidence to support the importance of small differences. One aspect of the invention provides methods, compositions, devices and algorithms for detecting Maintenance genes. The method comprises the step of measuring the expression of at least 50 genes, preferably 100 genes, more preferably more than 1000 genes, in a variety of tissues. The method further comprises the step of indicating that the gene is a Maintenance gene if the expression is the same in all the tissues of interest or in a subset of the tissues of interest. The term tissue, as used herein, is intended to describe a biological material from an organism. Therefore, an organ (or a homogenate of the organ), such the liver or kidney, may be referred to as a tissue. The methods are most suitable for simultaneously detecting a large number Maintenance genes. When it is used for simultaneous determination of a large number of Maintenance genes, the method includes the step of simultaneous monitoring of the expression of a large number of genes. Methods for monitoring a large number of genes are well known in the art and are described, for example, in the background section, supra. In some embodiments, the expression of a gene in a number of tissue is measured. The gene is considered as expressed at the same level if it is expressed in all the tissues at levels within ten folds, preferably within fourfold and more preferably within two fold. In some embodiments, a gene is considered as expressed at the same level if it is expressed in all tissues with no statistically difference. In the example that follows, genes were considered as expressed at the same level if they were expressed in all seven tissues at levels within fourfold. For most genes differences less than fourfold are probably not biologically significant but there is not enough data to conclude that a five or six-fold difference is more biologically significant than a three or four-fold difference (Cho, R. J., M. J. Campbell, E. A. Winzeler, L. Steinmetz, A. Conway, L. Wodicka, T. G. Wolfsberg, A. E. Gabrielian, D. Landsman, D. J. Lockhart, R. W. Davis. A Genome-Wide Transcriptional Analysis of the Miotic Cell Cycle. Molecular Cell, 2: 65-73, 1998; Creanor, J., J. M. Mitchinson. Nucleoside Diphosphokinase, An Enzyme With Step Changes in Activity During the Cell Cycle of the Fission Yeast Schizosaccharomyces Pombe. Journal of Cell Science 207-215, 1986; Klevecz, R. R.. The Scientist 22-24, 1999; Klevecz, R. R., S. A. Kaufman, R. M. Shymko, Cellular Clocks and Oscillators. International Review of Cytology, 86:97-128, 1984). For a subset of genes it is likely that small differences have biological relevance such as the genes encoding proteins that function differently when bound to high affinity versus low affinity receptors or gene products triggering cellular cascades (Merchav, S.. The Haematopoietic Effects of Growth Hormone and Insulin-Like Growth Factor-I. J. Pediatr. Endocrin. Metab. 11(6):677-685, 1998; Skerry, T. M. Identification of Novel Signaling Pathways During Functional Adaptation of the Skeleton to Mechanical Loading: The Role of Glutamate as a Paracrine Signaling Agent in the Skeleton. J. Bone Miner Metab. 17(1): 66-70, 1999).

Maintenance Genes:

In another aspect of the invention, a subset of genes expressed at the same level in each of seven major tissues are identified as housekeeping genes (See, Table 1). Most of these genes have never before been specifically identified as belonging in this category. This information is useful for establishing average normal expression levels and will be useful as a reference in studies of normal expression variation (i.e. www.HuGEindex.org.). In one aspect of the invention, the maintenance genes described are used to establish average normal expression levels. In some embodiments, the expression of at least one of the genes listed in table 1, preferably at least two of the genes listed in table 1, more preferably at least 10 of the genes listed in table 1, and even more preferably at least 100 of the genes listed in table 1 is monitored along with the expression of a target gene (gene of interest). The change of the level of expression of the target gene will be evaluated using the expression of the maintenance gene(s) as a control.

Example Identification of Maintenance Genes

Methods

Sample Preparation

All samples were prepared from pools of human adult poly(A) RNA purchased from Clontech (Palo Alto, Calif.). The tissues screened are listed followed by the number of tissues pooled and the Clontech catalog number in parenthesis. Heart, 3 (6533-1), brain, 5 (6516-1), lung, 5 (6524-1), kidney, 8 (6538-1), pancreas, 10 (6539-1), uterus, 10 (6537-1), testis, 19 (6535-1). Poly(A) RNA was amplified and labeled with biotin following the procedure described by Wodicka et al., 1997⁽³²⁾. First strand cDNA synthesis was carried out at 37° C. for 60 minutes. The amplified cRNA (target) was purified on an affinity resin (RNeasy, Qiagen) and quantitated.

Fragmentation, Array Hybridization and Scanning

Labeled target was fragmented by incubation at 94° C. for 35 minutes in the presence of 40 mM Tris-acetate pH 8.1, 100 mM potassium acetate, and 30 mM magnesium acetate. The hybridization solution consisted of 20 ug fragmented cRNA, 0.1 mg/ml sonicated herring sperm DNA in buffer containing 100 mM MES, 1 m[Na⁺], 20 mMEDTA, 0.01% Tween 20 (MES). The hybridization mixture was heated to 99° C. for 5 min. followed by incubation at 45° C. for 5 min. before injection of the sample into the probe array cartridge. All hybridizations were performed in duplicate and were carried out at 45° C. for 16-17 hr with mixing on a rotisserie at 60 rpm. Following hybridization, the solutions were removed, arrays were rinsed with 1×MES (100 mM MES, 1 m[Na⁺], 20 mMEDTA, 0.01% Tween 20). Subsequent washing and staining of the arrays was carried out using the GeneChip® fluidics station protocol EukGE_WS2. The EukGE_WS2 protocol included two post hybridization washes, staining, and a post stain wash. The first wash consisted of 10 cycles of 2 mixes per cycle with Non Stringent Wash Buffer (6×SSPE, 0.01% Tween 20, 0.005% Antifoam) at 25° C. The second wash consisted of 4 cycles of 15 mixes per cycle with Stringent Wash Buffer (100 mm MES, 0.1M [Na⁺], 0.01% Tween 20) at 50° C. The probe arrays were stained for 10 minutes in streptavidin-phycoerythrin solution (SAPE) (1×MES solution, 0.005% antifoam, 10 μg/ml SAPE (Molecular Probes, Eugene, OR) 2 μg/μl acetylated BSA (Sigma, St. Louis, Mo.) at 25° C. The post stain wash consisted of 10 cycles of 4 mixes per cycle at 25° C. The probe arrays were treated for 10 minutes in antibody solution (1×MES solution, 0.005% antifoam, 2 μg/μl acetylated BSA, 0.1 μg/μl normal goat IgG (Sigma Chemical, St. Louis Mo.), 3 μg/μl antibody (goat), antistreptavidin, biotinylated (Vector Laboratories, Burlingame, Calif.) at 25° C. The final wash consisted of 15 cycles of 4 mixes per cycle at 30° C. Following washing and staining, probe arrays were scanned 2 times (multiple image scan) at 3 μm resolution using the GeneChip® System confocal scanner made for Affymetrix Inc. by Hewlett Packard.

Probe Arrays

The arrays were synthesized using light-directed combinatorial chemistry as described previously. The Hu6.8K_all GeneChip® probe arrays used for the current study contain probe sets representing 7129 genes. The oligonucleotides are 25 bases in length. Probes are complementary and correspond to human genes registered in Unigene, GenBank and The Institute for Genomic Research Database (TIGR). Each probe set has oligonucleotides that are identical to sequence in the gene and oligonucleotides that contain a homomeric (base transversion) mismatch at the central base position of the oligomer used for measuring cross hybridization. Probes are selected with a bias toward the 3′ region of each gene. Probe pairs representing human genes such as GAPDH, B-actin, transferrin receptor and transcription factor ISGF-3 serve as internal controls for monitoring RNA integrity. In addition, the probe arrays contain oligonucleotides representing sequences of bacterial genes, BioB, BioC, BioD, and one phage gene, Cre, as quantitative standards. Copy numbers are determined by correlating the known concentrations of the spiked standards with their hybridization. Copies per cell are calculated based on the assumption that the average transcript length is 1 kb and there are 300,000 transcripts per cell.

Analysis

All samples were hybridized in duplicate and only those transcripts detected as present in duplicate hybridizations or absent in duplicate hybridizations are reported. Of the transcripts present in duplicate hybridizations the hybridization values were within two fold. The values from the duplicate hybridizations were averaged. GeneChip® 3.0 software was used to scan and analyze the data. Microsoft Excel and Microsoft Access were also used for data analysis.

Result

Using GeneChip® probe arrays (Affymetrix, Santa Clara, Calif.), 695 genes that are expressed in common among heart, brain, lung, kidney, pancreas, uterus and testis were identified. 241 of the genes were detected at similar levels in each of the tissues; 44 genes were detected at low abundance, 72 detected at low-moderate abundance, 100 at moderate abundance, 13 at moderate-high abundance, and 12 at high abundance (See Table 1). TABLE 1 Maintenance genes sorted by function. Abundance levels are binned by copies per cell where low, L, <5, low-moderate, LM > 5 < 10, moderate, M, > 10 < 50, moderate-high, MH, > 50 < 100, high, H, >100. Accession Abun- Number Description dance ATPase M37104 mitochondrial ATPase coupling M factor 6 subunit (ATP5A) U51478 sodium/potassium-transporting M ATPase beta-3 subunit Z71460 vacuolar-type H(+)-ATPase LM 115 kDa subunit Channels, pores D31846 aquaporin-2 water channel M L08666 porin (por) M Cytochrome AC002115 COX6B (COXG) on chromosome 19 M cosmids M22760 nuclear-encoded mitochondrial M cytochrome c oxidase Va subunit L32977 ubiquinol cytochrome c reductase M Rieske iron-sulphur protein X13238 cytochrome c oxidase subunit VIc M X16560 COX VIIc subunit VIIc of M cytochrome c oxidase M28713 NADH-cytochrome b5 reductase (b5R) LM Dehydrogenase D90086 pyruvate dehydrogenase M (EC 1.2.4.1) beta subunit D43682 very-long-chain acyl-CoA M dehydrogenase (VLCAD) U17886 succinate dehydrogenase LM iron-protein subunit (sdhB) U05861 hepatic dihydrodiol dehydrogenase L L13761 dihydrolipoamide dehydrogenase L DNA binding J03827 Y box binding protein-1 (YB-1) MH M26730 mitochondrial ubiquinone-binding M protein with an LTR-like sequence X75593 rab 13 M U79528 SR31747 binding protein 1 M L37368 RNA-binding protein M U33821 tax1-binding protein TXBP151 M Z29505 nucleic acid binding protein sub2.3 M U07857 18 kDa Alu RNA binding protein, M M94556 mitochondrial specific single LM stranded DNA binding protein N31 M28209 GTP-binding protein (RAB1) LM D13988 rab GDI LM U51334 putative RNA binding protein (RBP56), LM D43951 KIAA0099, (pumilio-like, putative LM DNA binding) U65928 Jun activation domain binding L protein Electron transfer X71129 electron transfer flavoprotein LM beta subunit J04058 electron transfer flavoprotein L alpha-subunit G protein related U20285 Gps1 (GPS1) M U45982 G protein-coupled receptor GPR-9-6 LM U31384 G protein gamma-11 subunit LM X81625 Cl1 protein L HLA D32129 HLA class-I (HLA-A26) heavy chain M X03100 HLA-SB alpha (class II antigen) M X75091 HLA-DR associated protein II L (PHAPII) Heat shock J04988 90 kD heat shock protein MH L15189 mitochondrial HSP75 LM Histone M11353 H3.3 histone class C MH U50079 histone deacetylase HD1 LM X05855 histone H3.3 L Interferons X57351 1-8D from interferon-inducible H family X59892 IFN-inducible gamma-2 protein M J00212 leukocyte interferon (ifn-alpha) L alpha-f Kinase M14676 src-like kinase (slk) M L08835 DM kinase (myotonic dystrophy M kinase) M30448 casein kinase II beta subunit LM Lysosome associated AJ000099 lysosomal hyaluronidase M U91932 AP-3 complex sigma3A subunit M M15182 beta-glucuronidase (lysosomal LM enzyme) M29877 alpha-L-fucosidase, (lysosomal LM enzyme) Membrane D29963 SFA-1, a member of transmembrane 4 M superfamily L10284 IP90, integral membrane protein, M calnexin U57877 nuclear-encoded mitochondrial LM integral membrane protein CII-3 Metabolism D78361 ornithine decarboxylase antizyme H M33764 ornithine decarboxylase amino acid M metabolism HG2279- Triosephosphate Isomerase M HT2375 U86070 phosphomannomutase (carbohydrate LM metabolism) U32114 caveolin-2 (lipid metabolism) L Mitochondrial associated Z70759 mitochondrial 16S rRNA H M22538 nuclear-encoded mitochondrial M NADH-ubiquinone reductase 24 kD subunit M22760 nuclear-encoded mitochondrial M cytochrome c oxidase Va subunit X60036 mitochondrial phosphate carrier M protein M37104 mitochondrial ATPase coupling M factor 6 subunit (ATP5A) M26730 mitochondrial ubiquinone-binding M protein with an LTR-like sequence X99728 NDUFV3, mitochondrial NADH M ubiquinone oxidoreductase U59309 nuclear-encoded mitochondrial LM fumarase precursor (FH) L15189 mitochondrial HSP75 LM M94556 mitochondrial specific single LM stranded DNA binding protein U57877 nuclear-encoded mitochondrial LM integral membrane protein CII-3 L07033 hydroxymethylglutaryl-CoA lyase LM U15174 Nip3 (NIP3) (mitochondrial, L pro-apoptotic protein family) Phosphatase U45975 phosphatidylinositol (4,5) M bisphosphate 5-phosphatase homolog X74008 phosphatase 1 gamma LM X81003 HCG V (phosphatase inhibitor) LM M65254 phosphatase 2A 65 kDa regulatory L subunit-beta Polymerase Z27113 RNA polymerase II subunit 14.4 kD M U37690 RNA polymerase II subunit (hsRPB10) M Z47727 RNA polymerase II subunit LM Protease, proteinase related L02426 26S protease (S4) regulatory subunit M M23254 Ca2-activated neutral protease M large subunit (CANP) X12451 pro-cathepsin L (major excreted M protein MEP) S69272 cytoplasmic antiproteinase, 38 kD M intracellular serine proteinase inhibitor Proteasome D29012 proteasome subunit Y M D26598 proteasome subunit HsC10-II M D26599 proteasome subunit HsC7-I M D38047 26S proteasome subunit p31 M AB003177 proteasome subunit p27 LM D00763 proteasome subunit HC9 LM D50063 proteasome subunit p40_/Mov34 LM protein, X61970 macropain subunit zeta (proteasome) LM X95586 MB1 LM D00760 proteasome subunit HC3 L D00762 proteasome subunit HC8 L Receptor and receptor associated proteins M63959 alpha-2-macroglobulin receptor- M associated protein D23673 insulin receptor substrate-1-like M (IRS-1) X07979 fibronectin receptor beta subunit M U83239 CC chemokine STCP-1 (immune M function, T-receptor assoc) M88279 immunophilin (FKBP52) M U45982 G protein-coupled receptor GPR-9-6 LM X56253 MPR46 46 kd mannose 6-phosphate LM receptor X80763 5-HT2c receptor LM L40357 thyroid receptor interactor (TRIP7) L Reductase M22538 nuclear-encoded mitochondrial M NADH-ubiquinone reductase 24 kD subunit X91247 thioredoxin reductase LM X15414 aldose reductase (EC 1.1.1.2) LM M28713 NADH-cytochrome b5 reductase (b5R) LM Repair U07418 DNA mismatch repair (hmlh1) L U49785 D-dopachrome tautomerase LM Replication J05249 replication protein A 32-kD subunit LM Ribonucleoprotein HG3076- heterogeneous nuclear M HT3238 ribonucleoprotein K, alt. splice 1 X16135 novel heterogeneous nuclear M RNP protein, L protein X78136 hnRNP-E2 M M94630 hnRNP-C like protein M M16342 nuclear ribonucleoprotein LM particle (hnRNP) C protein Z23064 hnRNP G protein L Ribosomal X81625 ribosomal protein L37a (RPL37A) H Z12962 homologue to yeast ribosomal H protein L41 HG3214- Metallopanstimulin, MPS-1 (S27 H HT3391 Zinc finger) HG1800- ribosomal protein S20 H HT1823 U14973 ribosomal protein S29 H Z26876 ribosomal protein L38 MH M77232 ribosomal protein S6 MH HG821- ribosomal protein S13 MH HT821 M13934 RPS14, ribosomal protein S14 MH Ribosylation M84332 ADP-ribosylation factor 1 M M36341 ADP-ribosylation factor 4 (ARF4) LM Signal transduction D49396 Apol (MER5-like protein) L Structure U57341 neurofilament triplet L protein MH Z19554 vimentin MH X51521 ezrin M HG2238- nuclear mitotic apparatus protein M HT2321 1, alt. splice form 2 M64571 microtubule-associated protein 4 M M31013 nonmuscle myosin heavy chain (NMHC) M V00599 fragment encoding beta-tubulin M (D-beta-1) U24105 coatomer protein (HEPCOP), M M95627 angio-associated migratory cell LM protein (AAMP) D38549 KIAA0068 LM U56637 capping protein alpha subunit LM isoform 1 X72964 caltractin LM X70476 subunit of coatomer complex LM D28915 hepatitis C-associated microtubular L aggregate protein p44 X82103 beta-COP L Synthases and synthetases D14710 ATP synthase alpha subunit MH X76013 QRSHs, glutaminyl-tRNA synthetase M X83218 ATP synthase M X60221 H+-ATP synthase subunit b M D31890 KIAA0070 M U09510 glycyl-tRNA synthetase LM U79262 deoxyhypusine synthase LM J03473 poly(ADP-ribose) synthetase LM X94754 yeast methionyl-tRNA synthetase LM homologue Transcription L49380 transcription factor ZFM1 M U95040 transcriptional corepressor M hKAP1/TIF1B U10323 nuclear factor NF45 M L12168 adenylyl cyclase-associated M protein (CAP), M97935 transcription factor ISGF-3 LM sequence X52882 t-complex polypeptide 1 LM L19067 NF-kappa-B transcription factor L p65 subunit D63478 KIAA0144 L U15782 cleavage stimulation factor 77 kDa L subunit (polyadenylation) L20298 transcription factor (CBFB) L Transferase U56417 lysophosphatidic acid M acyltransferase-alpha U62739 branched-chain amino acid M aminotransferase (ECA40) Y08200 rab geranylgeranyl transferase, M alpha-subunit U82010 heme A: farnesyltransferase (COX10) LM U86529 glutathione transferase Zeta 1 LM (GSTZ1) D26535 dihydrolipoamide L succinyltransferase Transformation related U50523 BRCA2 region M U57342 myelodysplasia/myeloid leukemia M factor 2 (MLF2), HG4541- transformation-related protein M HT4946 M15990 c-yes-1 L L12535 RSU-1/RSP-1 (Ras suppressor) L Translation, inititiation and elongation J04617 elongation factor EF-1-alpha H X51466 elongation factor 2 MH L26247 sui 1, N278 iso1 MH U46025 translation initiation factor M eIF-3 p110 subunit X55733 initiation factor 4B LM X98743 RNA helicase (Myc-regulated L dead box protein) Transport U36341 SLC6A8 (creatine transporter) M U51478 sodium/potassium-transporting M ATPase beta-3 subunit X81817 BAP31 (ER, protein sorting) M Y00281 ribophorin I (ER) M Y00282 ribophorin II (ER) M U70660 copper transport protein HAH1 LM U41740 trans-Golgi p230 LM X12791 signal recognition particle, L SRP 19 kD protein (ER) Ubiquitin related X56997 UbA52 coding for ubiquitin-52 MH amino acid fusion protein M26880 ubiquitin M U46751 phosphotyrosine independent M ligand p62 for the Lck SH2 domain U39317 E2 ubiquitin conjugating enzyme L UbcH5B (UBCH5B), Zinc finger HG3214- Metallopanstimulin, MPS-1 (S27, H HT3391 Zinc finger) X70394 OZF L U09412 zinc finger protein ZNF134 L HG3454- zinc finger protein 20 L HT3647 Undefined X67698 unknown product M L11066 unknown product M U79294 unknown product M D28124 unknown product M D21261 KIAA0120 M D87451 KIAA0262 M D14694 KIAA0024 M ISGF3A/ unknown product LM M97935 L20773 unknown product LM D42043 KIAA0084 LM D50911 KIAA0121 LM D79994 KIAA0172 LM D29643 KIAA0115 LM D14662 KIAA0106 LM D86963 KIAA0208 LM D21853 KIAA0111 LM D63476 KIAA0142 LM D42087 KIAA0118 L D30756 KIAA0049 L D80004 KIAA0182 L D79993 KIAA0171 L L40395 unknown product L Others X98482 TNNT2, (troponin) H U06155 chromosome 1 q subtelomeric H sequence M33680 26-kDa cell surface protein TAPA-1 H M13450 esterase D M U11861 G10 homolog, edg-2 M U62317 hypothetical protein 384D8_2 M on chromosome 22q13 (other) HG3991- Cpg-enriched DNA (other) M HT4261 X80199 MLN51 M X80200 MLN62 M U46570 tetratricopeptide repeat protein M (tpr1) N297 (other) HG3597- major histocompatibility complex, M HT3800 class I X71428 fus (nuclear RNA binding protein) M U73824 p97 M Y00433 glutathione peroxidase (peroxide M clearance) U02493 54 kDa protein M U88964 HEM45 LM D78129 squalene epoxidase (sterol LM biosynthesis) D43951 KIAA0099, (pumilio-like, putative LM DNA binding) X96484 DGCR6 protein (organization, LM migration during development) HG1155- colony-stimulating factor 1, LM HT4822 macrophage, alt. splice 3 L38932 GT197 N305 LM X66397 tpr LM L42572 p87/89 (ER transmembrane protein) LM X80695 OXA1Hs (cytochrome oxidase assembly) LM Y00097 p68 (membrane associated, calcium LM binding protein) Z48042 GPI-anchored protein p137 LM Z35093 SURF-1 (Surfeit gene family, LM biogenesis of cytochrome C oxidase) U54644 tub homolog LM Z93784 mouse brain protein E46-like L sequence L38616 brain and reproductive organ- L expressed protein (BRE) D63506 unc-18 homologue L U18009 human gene on chromosome 17q21 L L27476 X104 (membrane associated, L kinase containing protein family) M73720 mast cell carboxypeptidase A L (MC-CPA) For example, no difference in expression level was detected for 5 of the genes and a two-fold difference was detected for 46 of the genes. 454 genes are expressed in all seven tissues but vary in expression level by more than fourfold. 333 of the genes vary in expression level by 5-10 fold. Included in this subset are genes frequently used as controls in standard expression analysis including beta actin (M10277) varying by 7-fold with highest expression in brain and uterus and lowest expression in heart, and GAPDH (M33197) varying by 8-fold with highest expression in brain, heart and kidney and lowest in pancreas. Another form of beta actin (X00351) varied by 22-fold with highest expression in uterus and lowest in pancreas. Alpha actin (X13839) varied by 23-fold and gamma actin (M19283) by 9-fold. 40 genes expressed in all seven tissues differ in transcript levels by greater than 19 fold and of these eight differ by more than 50-fold, including COX7A muscle isoform (M83186) varying by 52-fold, highest in heart, lowest in kidney, pancreas and testis, lectin (J04456) varying by 58-fold, highest in uterus, lowest in kidney and pancreas, myosin heavy chain (AF001548) varying by 61-fold, highest in uterus, lowest in brain and pancreas, elongation factor-1 delta (Z21507) varying by 69-fold, highest in pancreas, lowest in lung and kidney, RNA polymerase II elongation protein (Z47087) varying by 70-fold, highest in brain, lowest in pancreas, extracellular mRNA for glutathione peroxidase (D00632) varying by 78-fold, highest in kidney, lowest in brain, pancreas and testis, 14-9-9 protein eta chain (D78577) varying by 81-fold, highest in brain, lowest in testis, and L-arginie:glycine amidinotransferase (S68805) varying by 133-fold, highest in pancreas and lowest in heart and lung.

In the same experiments, genes expressed uniquely in each of the seven tissues were also identified (Table II). For instance, in heart there were 4 transcripts not detected in the other 6 tissues; muscle glycogen synthase (J04501), NADH oxidoreductase subunit (L04490), MLC-1V/Sb isoform (M24248) and cytokine inducible nuclear protein (X83703). Twenty nine uniquely expressed transcripts were identified in the kidney including many that are expected such as potassium channel ROM-K3 (U65406) and renal Na/Pi cotransporter (L13258) as well as genes of unknown function such as a gene that maps to chromosome 19 (U95090). 45 uniquely expressed transcripts were detected in uterus, 28 in pancreas and 19 in lung. Not surprisingly, the greatest number of uniquely expressed genes, 91 and 94 respectively, were found in brain and testis. TABLE II Genes Uniquely Expressed in a Comparison of Eleven Human Tissues Accession No. Description Bin* Uniquely Expressed in Adult Heart J04501 Muscle glycogen synthase M M24248 MLC-1V/Sb isoform M X83703 Cytokine inducible nuclear protein LM Uniquely Expressed in Fetal Kidney D88532 P55pik L M26901 Renin M M81829 Somatostatin receptor isoform 1 L U19107 ZNF127 L U19906 Arginine vasopressin receptor 1 (AVPR1) L U34301 Nonmuscle myosin heavy chain IIB LM X58431 HOX 2.2 M Z67743 CLC-7 chloride channel protein LM Uniquely Expressed in Fetal Liver AF000573 Homogentisate 1,2-dioxygenase LM D00097 Amyloid P component (SAP) M D16611 Coproporphyrinogen oxidase M D16626 Histidase M D21063 KIAA0030 M D26361 KIAA0042 L D38535 PK-120 H D38537 Protoporphyrinogen oxidase M D42055 KIAA0093 L D49357 S-adenosylmethionine synthetase LM D49742 HGF activator like protein M D79988 KIAA0166 L D84454 UDP-galactose translocator LM D87116 MAP kinase kinase 3b M D90282 Carbamyl phosphate synthetase I MH (EC 6.3.4.16) HG1148- Lipopolysaccharide-Binding Protein H HT1148 HG1227- Collagen, Type II, Alpha 1 M HT1227 HG1649- Elastase 1 M HT1652 HG2730- Fibrinogen, A Alpha Polypeptide, H HT2827 Alt. Splice 2, E HG3105- Atpase, Cu2+ Transporting L HT3281 HG3565- Zinc Finger Protein M HT3768 HG627- Rhesus (Rh) Blood Group System MH HT5097 Ce-Antigen, Alt. Splice 2, Rhvi J00116 Collagen COL2A1 M J02982 Glycophorin B MH J03474 Serum amyloid A H J03626 UMPS L J05070 Type IV collagenase L J05500 Beta-spectrin (SPTB) M K01383 Metallothionein-I-A MH K02402 Coagulation factor IX M L00190 Antithrombin III (ATAIII) H L01664 Eosinophil Charcot-Leyden crystal L (CLC) protein (lysophospholipase) L06133 Putative Cu++-transporting L P-type ATPase L09708 Complement component 2 (C2), allele b MH L11244 C4b-binding protein beta-chain M L31860 Glycophorin A, MN-types (GYPA) M L32140 Afamin M L34081 Bile acid CoA: Amino acid LM N-acyltransferase L48516 Paraoxonase 3 (PON3) M L76571 Nuclear hormone receptor (shp) M L77567 Mitochondrial citrate transport M protein (CTP) M10014 Fibrinogen gamma chain and gamma- H prime chain M10058 Asialoglycoprotein receptor H1 M M10950 Alpha-fetoprotein (AFP) M M11025 Asialoglycoprotein receptor H2 M M11567 Angiogenin and three Alu repetitive M sequences M13699 Ceruloplasmin (ferroxidase) MH M14091 Thyroxine-binding globulin M M15205 Thymidine kinase with clustered M Alu repeats in the introns M16961 Alpha-2-HS-glycoprotein alpha and H beta chain M16967 Coagulation factor V M M16973 Complement protein C8 beta subunit M M17262 Prothrombin (F2) gene, and Alu and H KpnI repeats M19481 Follistatin LM M19828 Apolipoprotein B-100 (apoB) H M20786 Alpha-2-plasmin inhibitor MH M22638 LYL-1 protein M M22898 Phosphoprotein p53 L M27819 Anion exchange protein 1 (AE1, band 3) MH M29194 Triglyceride lipase M M36803 Hemopexin H M58569 Fibrinogen alpha-subunit bipartite H transcript of extended (alpha-E) variant M58600 Heparin cofactor II (HCF2), exons 1 H through 5 M59820 Granulocyte colony-stimulating LM factor receptor (CSF3R) M60298 Erythrocyte membrane protein band 4.2 MH (EPB42) M61827 Leukosialin (CD43) LM M61855 Cytochrome P4502C9 (CYP2C9), clone 25 L M64554 F13A1 gene (coagulation factor XIIIb) M M68895 Alcohol dehydrogenase 6 L M71243 Glycophorin Sta (type A) exons 3 and 4 MH M75106 Prepro-plasma carboxypeptidase B MH M86873 Type A plasminogen related M S42457 Photoreceptor cGMP-gated channel L S48983 SAA4, serum amyloid A M S70004 Glycogen synthase LM S72370 Pyruvate carboxylase LM S77393 Transcript ch138 LM S77763 Nuclear factor erythroid 2 M S77893 Glycophorin SAT MH S78234 Nuc2 homolog LM U00001 Homologue of S. pombe nuc2+ L and A. nidulans bimA U01317 Epsilon-globin LM U05255 Glycophorin HeP2 H U08006 Complement 8 alpha subunit (C8A) M U12778 Acyl-CoA dehydrogenase LM U13061 Dehydroepiandrosterone L sulfotransferase (STD) U14518 Centromere protein-A (CENP-A) L U18919 Clone pOV-2 L U20530 Bone phosphoprotein spp-24 precursor M U20979 Chromatin assembly factor-I L p150 subunit U32989 Tryptophan oxygenase (TDO) M U61836 Putative cyclin G1 interacting protein M U65404 Erythroid-specific transcription M factor EKLF U72515 C3f M U73167 H_LUCA14.2a M U73524 Putative ATP/GTP-binding protein (HEAB) L U90544 Sodium phosphate transporter (NPT3) M V01514 Alpha-fetoprotein (AFP) H X02176 Complement component C9 M X02544 Alpha1-acid glycoprotein (orosomucoid) H X03473 Histone H1(0) M X04898 Apolipoprotein H X05309 C3b/C4b receptor (CR1) F allotype L X06482 Theta 1-globin M X06562 Growth hormone receptor L X13293 B-myb M X13589 Aromatase (estrogen synthetase) LM X14329 Carboxypeptidase N small subunit LM (EC 3.4.17.3) X14690 Plasma inter-alpha-trypsin inhibitor H heavy chain H(3) X15422 Mannose-binding protein C M X16260 Inter-alpha-trypsin inhibitor H subunit 3 X16983 Integrin alpha-4 subunit L X17059 NAT1 gene for arylamine L N-acetyltransferase X17254 Transcription factor Eryf1 M X51688 Cyclin A LM X53414 Peroxisomal L-alanine: glyoxylate MH aminotransferase X55668 Proteinase 3 M X56692 C-reactive protein M X56741 Rab8 L X58199 Beta adducin M X59618 RR2 small subunit ribonucleotide LM reductase X59711 CAAT-box DNA binding protein subunit A L X59812 CYP 27 vitamin D3 25-hydroxylase M X62822 Beta-galactoside alpha-2,6- LM sialyltransferase X63097 Rhesus polypeptide (RhXIII) L X64594 Erythrocyte plasma membrane MH glycoprotein X64877 Serum protein LM X65550 Antigen of monoclonal antibody Ki-67 L X74330 DNA primase (subunit p48) L X75315 Seb4B M X77737 Red cell anion exchanger (EPB3, AE1, H Band 3) X80907 P85 beta subunit of M phosphatidyl-inositol-3-kinase X91148 Microsomal triglyceride transfer LM protein X98337 Complement factor H-related protein 4 M Y00317 Liver microsomal UDP- LM glucuronosyltransferase (UDPGT) Z15005 CENP-E LM Z26248 Eosinophil granule major basic LM protein Z28339 Delta 4-3-oxosteroid 5 beta- LM reductase Z32684 XK membrane transport protein M Z83821 DNA sequence from PAC 296K21 on H chromosome X contains cytokeratin exon, delta-aminolevulinate synthase (erythroid); 5-aminolevulinic acid synthase Z84721 DNA sequence from cosmid GG1 H from a contig from the tip of the short arm of chromosome 16, spanning 2Mb of 16p13.3 Uniquely Expressed in Fetal Lung D87071 KIAA0233 LM HG4638- Spliceosomal Protein Sap 49 L HT5050 U18671 Stat2 L U40434 Mesothelin or CAK1 antigen precursor LM X52896 Dermal fibroblast elastin M X97748 PTX3 LM Uniquely Expressed in Adult Brain D87463 KIAA0273 M HG2259- Tubulin, Alpha 1, Isoform 44 M HT2348 HG3437- Myelin Proteolipid Protein, H HT3628 Alt. Splice 2 L00354 Cholecystokinin (CCK) M L76224 NMDA receptor M L76627 Metabotropic glutamate receptor 1 L alpha (mGluR1alpha) M55267 EV12 protein LM M59488 S100 protein beta-subunit M S50017 2′,3′-cyclic nucleotide M 3′-phosphodiesterase S69965 Beta-synuclein M U01824 Glutamate/aspartate transporter II M U06698 Neuronal kinesin heavy chain LM U27768 RGP4 M U62801 Protease M M U82532 GDI-dissociation inhibitor RhoGDIgammma LM X59065 FGF, exon 3 M X64810 PC1/PC3 LM X73882 E-MAP-115 LM X99076 NRGN, exons 2, 3 & 4 (joined CDS) H Z48051 Myelin oligodendrocyte M glycoprotein (MOG) Uniquely Expressed in Adult Kidney J04093 Phenol UDP-glucuronosyl-transferase LM (UDPGT) L13258 Renal Na/Pi-cotransporter M M19878 Calbindin 27, exons 1 and 2, and Alu M repeat S77576 ERV9 reverse transcriptase homolog L (clone RT18) U17418 Hormone/parathyroid hormone-related M peptide receptor X13227 D-amino acid oxidase M X60708 PcHDP7, liver dipeptidyl peptidase IV L Uniquely Expressed in Adult Uterus D21337 Collagen L D86961 KIAA0206 L HG721- Placental Protein 14, Endometrial M HT4828 Alpha 2 Globulin, Alt. Splice 3 L00205 K6b (epidermal keratin, type II) L L02785 Colon mucosa-associated (DRA) L L06419 Lysyl hydroxylase (PLOD) LM L08044 Intestinal trefoil factor LM L10343 Elafin M L14848 MHC class I-related protein L M19888 Small proline rich protein (sprI) M M21121 T cell-specific protein (RANTES) L M21389 Keratin type II (58 kD) M M55543 Guanylate binding protein isoform II L (GBP-2) M59979 Prostaglandin endoperoxide synthase L M60284 Neurokinin A receptor (NK-2R) LM M62783 Alpha-N-acetylgalactosaminidase L M85276 NKG5 M M86757 Psoriasin M M86849 Connexin 26 (GJB2) L M96233 Transferase class mu number 4 (GSTM4) LM S66896 Squamous cell carcinoma antigen, L serine protease inhibitor S72493 Keratin 16 homolog M S81661 Keratinocyte growth factor L U07969 Intestinal peptide-associated L transporter HPT-1 U09278 Fibroblast activation protein L U09584 PL6 protein (PL6) L U11717 Calcium activated potassium channel L (hslo) U24488 Tenascin-X (XA) M U25138 MaxiK potassium channel beta subunit M U37283 Microfibril-associated glycoprotein-2 M MAGP-2 U43185 Signal transducer and activator L of transcription Stat5A U60325 DNA polymerase gamma, nuclear gene L encoding mitochondrial protein U76764 CD97 LM U81523 Endometrial bleeding associated M factor X03635 Oestrogen receptor M X06256 Fibronectin receptor alpha subunit LM X07695 Cytokeratin 4 C-terminal region M X07696 Cytokeratin 15 L X16662 Vascular anticoagulant-beta (VAC-beta) L X54162 64 Kd autoantigen expressed in M thyroid and extra-ocular muscle X63629 P cadherin L X75535 PxF protein L X83857 Prostaglandin E receptor (EP3a1) L X92521 MMP-19 protein L X93510 37 kDa LIM domain protein LM X96719 AICL (activation-induced C-type lectin) LM X98311 Carcinoembryonic antigen, CGM2 L Y07755 S100A2, exon 1, 2 and 3 M Uniquely Expressed in Adult Testis D17570 Zona-pellucida-binding protein (sp38). M D50925 KIAA0135 L D64109 Tob family L D78333 Testis-specific TCP20 M D78334 Ankyrin motif MH HG2075- Camp-Responsive Element Modulator, M HT2137 Alt. Splice 1 HG36- Polymyositis/Scleroderma (Pm-Scl) L HT4101 Autoantigen, Alt. Splice 2 HG3725- Insulin-Like Leydig Hormone M HT3981 HG4316- Transketolase-Like Protein L HT4586 L01042 HIV1 tata element modulatory factor L L07515 Heterochromatin protein homologue (HP1) LM L14754 DNA-binding protein (SMBP2) LM L22214 Denosine A1 receptor (ADORA1), L exons 1-6 L36861 Guanylate cyclase activating protein L (GCAP), exons 1-4 L42324 G protein-linked receptor (GPCR) L L76687 Grb14 L M13981 Inhibin A-subunit M M14565 Cholesterol side-chain cleavage enzyme L P450scc M21539 Small proline rich protein (sprII) L M31606 Phosphorylase kinase (PSK-C3) M M63256 Major Yo paraneoplastic antigen (CDR2) L M73077 Glucocorticoid receptor repression LM factor 1 (GRF-1) M86808 Pyruvate dehydrogenase complex (PDHA2) L M91438 Kazal-type serine proteinase (HUSI-II) M S68134 CREM, cyclic AMP-responsive element LM modulator beta isoform S78873 Zn2+ binding protein/guanine L nucleotide exchange factor U03644 Recepin L U10362 GP36b glycoprotein L U13680 Lactate dehydrogenase-C (LDH-C) M U15422 Protamine 1 (PRM1), protamine 2 (PRM2) H and transition protein 2 (TNP2) U17032 P190-B (p190-B) L U17280 Steroidogenic acute regulatory protein LM (StAR) U19147 GAGE-6 protein LM U20362 Tg737 LM U22815 LAR-interacting protein 1a L U31929 Orphan nuclear receptor (DAX1) L U38175 HuR RNA binding protein (HuR) L U41763 Muscle specific clathrin heavy chain L (CLTD) U43944 Breast cancer cytosolic NADP(+)- L dependent malic enzyme U47054 Putative mono-ADP-ribosyltransferase LM (htMART) U58970 Putative outer mitochondrial membrane M 34 kDa Translocase hTOM34 U60665 Testis specific basic protein (TSBP) L U65011 Preferentially expressed antigen of LM melanoma (PRAME) U65092 Melanocyte-specific gene 1 (msg1) M U65533 Regulator of nonsense transcript L stability (RENT1) U65918 Putative RNA binding protein (DAZH) L U66726 Testis specific RNA binding protein LM (SPGYLA) U70981 Interleukin-13 receptor L U78722 Zinc finger protein 165 (Zpf165) L U79266 Clone 23627 L U84720 Export protein Rael (RAE1) LM U89606 Pyridoxal kinase M X04445 InhA gene exon 1 (and joined CDS) LM X05246 Testis-specific PGK-2 gene for M phosphoglycerate kinase (ATP: 3-phospho-D-glycerate 1-phosphotransferase, EC 2.7.2.3) X07948 Transition protein 1 (TP1) H X12433 PHS1-2, ORF homologous to membrane LM Receptor proteins X14968 RII-alpha subunit of cAMP dependent L protein kinase X68285 Glycerol kinase L X69398 OA3 antigenic surface determinant L X70218 Protein phosphatase X LM X78706 Carnitine acetyltransferase M X78711 Glycerol kinase testis specific 1 L X78712 Glycerol kinase testis specific 2 M X79200 SYT-SSX, synovial sarcoma M translocation junction X89960 Mitochondrial capsule selenoprotein M X95239 Cysteine-rich secretory protein-2/ M type I X99374 Fertilin beta L Y00970 Acrosin (EC 3.4.21.10) M Y12856 AMP-activated protein kinase alpha-1 L Z22780 Cylicin L Z46788 Cylicin II L Z46967 Calicin M Z48570 Sp17 LM Z49105 HD21 M Z50115 Thimet oligopeptidase L (metalloproteinase) Z75190 Apolipoprotein E receptor 2. L Uniquely Expressed in Fetal Brain HG1996- Guanine Nucleotide-Binding Protein LM HT2044 Rap2, Ras-Oncogene Related HG4063- Transcription Factor Hbf-2 M HT4333 L07919 Homeodomain protein DLX-2 M L13744 AF-9 LM M64358 Rhom-3 LM M88461 Neuropeptide Y peptide YY receptor M U00802 Drebrin E2 (DBN1) M U04735 Microsomal stress 70 protein ATPase L core (stch) U09413 Zinc finger protein ZNF135 L U11701 LIM-homeobox domain protein (hLH-2) M U35234 Protein tyrosine phosphatase sigma M U43843 H-neuro-d4 protein M U64871 Putative G protein-coupled receptor L (GPR19) U66198 Fibroblast growth factor homologous M factor 2 (FHF-2) U79247 Clone 23599 LM U81262 Lerk-5 (Lerk-5) LM X95425 EHK-1 receptor tyrosine kinase L Z11933 N-Oct 3, N-Oct5a, and N-Oct 5b proteins M Z70220 Unknown protein (clone ICRFp507O0882) M Uniquely Expressed in Adult Pancreas AF014958 Chemokine receptor X (CKRX) LM D31797 CD40 ligand (CD40L) LM J00268 Insulin H J02883 Colipase H J05125 Triglyceride lipase H L08010 Reg gene homologue H L14813 Carboxyl ester lipase like protein MH (CELL) M16652 Pancreatic elastase IIA H M16653 Elastase IIB H M21056 Pancreatic phospholipase A-2 (PLA-2) H M22612 Pancreatic trypsin 1 (TRY1) H M24349 Parathyroid hormone-like protein (PLP) L M24400 Chymotrypsinogen H M55131 Cystic fibrosis transmembrane M conductance regulator (CFTR) M74096 Long chain acyl-CoA dehydrogenase L (ACADL) M81057 Procarboxypeptidase B H M93284 Pancreatic lipase related protein 2 H (PLRP2) S82198 Caldecrin, serum calcium-decreasing H factor X54457 Bile-salt-stimulated lipase (BSSL) H X67318 Procarboxypeptidase A1 H X71877 Chymotrypsin-like protease CTRL-1 H Y00705 Pancreatic secretory inhibitor H (expressed in neoplastic tissue) Y08134 ASM-like phosphodiesterase 3b LM *The abundance levels in copies per cell: L < 5, LM > 5 < 10, M > 10 < 50, MH > 50 < 100, H > 100.

Conclusion

The present invention provides methods and compositions for identifying and using maintenance genes. It is to be understood that the above description is intended to be illustrative and not restrictive. Many variations of the invention will be apparent to those of skill in the art upon reviewing the above description. By way of example, the invention has been described primarily with reference to the use of a high density oligonucleotide array, but it will be readily recognized by those of skill in the art that other nucleic acid arrays, other methods of measuring transcript levels and gene expression monitoring at the protein level could be used. The scope of the invention should, therefore, be determined not with reference to the above description, but should instead be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

All references cited in this application are incorporated by reference for all purposes. 

1. A method for identifying a maintenance gene comprising: determining the expression of at least one hundred genes in at least two different types of tissues in two different developmental stages; and indicating a gene that is expressed at the same level in said tissues in said stages as said maintenance gene. 2-12. (Cancelled) 